Thread: Super annoying low coolant alarm going off until car warms up (earth issue??)

Originally Posted by AK83

Did you have the reservoir cap on?
If so, maybe the lack of additional air pressure on the higher water level in the reservoir(ie. a partial vacuum) could have stopped the flow out the radiator?
Dunno! every time I open the rad plug, I also have the reservoir cap off too.. and it flows out.
Other possible reasons is the level in the reservoir. While it's not a lot higher, it's still higher than the top of the rad, and a full reservoir should drain out with the rad cap off.

'good' to see some rust on that sensor doodad .. to be sure! not good that it's rusted! .. good in the sense that hopefully it's the source of your annoying issue.

What I do for the rad: reservoir cap off, rad bung(or in your case, the sensor) half on/off so that it leaks.
Fill reservoir continuously so that you get a flow out of the half fitted rad cap.
In a sense, your trying to expel any air in the rad too. Hopefully the rad sensor cap thing is an easy hand tightening job too and as you pour water/coolant into the reservoir slowly tighten the rad cap too.

With that rust on the sensor, there is a possibility that you may have rusty scale build up in your coolant system too. If so, it could clog up the rad.

**additional useless info **
A few weeks ago my CEM products came in the mail and the first thing I did was to test the coolant flush stuff. Left it in for a day or so to circulate around then did a flush with the garden hose.
Old coolant came out much more brown that I used to see it in the reservoir which was basically clean water(I've been using straight water for the past year or so).
So this CEM stuff has definitely cleaned something out of the cooling system. When I flushed the rad too, in both directions with the hose, brown coloured water came out from the bottom hose port, but clear water coming out of the top!
Obviously some build up in the bottom of the rad. I reckon I had to back flush the rad at least 10-15 mins alternating between forward and back flushing to clear the flow out the bottom.
Engine basically flowed clean, with some residual green coolant in there.

Actually ended up with a bit of an improvement in coolant temps, which was what I'm chasing .. only with thee A/C on.
Without A/C on, coolant temps stick to high 70's - low 80's without fail, no matter the engine load.

With A/C, in mid 30's ambient, coolant would easily pass 100°C on an easy cruise. Add even a slight rise in the road, and 105° would come quickly and then the dash gauge would climb towards the red, never actually go into the red .. just an indication that it's warming up.
I'd have to both back off almost totally, and turn A/C off and it'd settle back down to about mid to high 90's for a long while after that.. it was hard to moderate the use of the A/C as it's get hot so quickly with it on .. etc.

Other week I went for a bit of a drive .. lots of 40°C ambients between Cobar/Wilcannia/Broken Hill/and Menindee.
I got many instances of 700°C EGT temps which had me backing right off and dropping into 3rd(auto) to keep them in check, but coolant temp never passed 100°C and only hit that 100°C temp for a split sec. Mainly sat at about 95-97°C according to the data log.

I suspect that the bottom of the rad was partially blocked!

Did the chap in Monbulk give the coolant a refresh/flush/etc? was that part of the service?
Did he refill with coolant? ie. do you have coolant in the system.
I'd suggest(with the rust on that sensor) to give the coolant a flush while you're there doing all this other stuff.

ps. you can run straight water too .. don't really need coolant, they say it supposed to help with boiling point level, but the trick is to not allow it to get to boiling point!
Like I said, I've been running straight water for over a year now.
Will eventually top with coolant(got a large 20lt drum of it now) .. just been lazy and more accurately I'm still in between flushing phases AND trying to get off the posterior to do my silicon hoses change.

Yep the other caps were all still on so I guess there is no other hole to allow anything out of the system, even though it may be lower in height.

The radiator got totally taken out and flushed and checked and had it's own personal pampering service done on it. Apparently it was 40% blocked but still in great nick so they gave it a good proper clean out and put it back on and put all new coolant (with all new hoses as well) and bled the system etc. etc. So I've got no doubts the radiator is clean and lovely.

All pretty full too